diff --git a/CHANGELOG.md b/CHANGELOG.md
index cd8027b050..cae884793b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -22,6 +22,7 @@
 ### Server
 - Fix: プロフィール追加情報で無効なURLに入力された場合に照会エラーを出るのを修正
 - Fix: ActivityPubリクエストURLチェック実装は仕様に従っていないのを修正
+- Fix: 連合無しモードでも外部から照会可能だった問題を修正
 
 ## 2025.3.1
 
diff --git a/packages/backend/src/server/ActivityPubServerService.ts b/packages/backend/src/server/ActivityPubServerService.ts
index 20e985aaf2..48c80e5e61 100644
--- a/packages/backend/src/server/ActivityPubServerService.ts
+++ b/packages/backend/src/server/ActivityPubServerService.ts
@@ -13,7 +13,7 @@ import accepts from 'accepts';
 import vary from 'vary';
 import secureJson from 'secure-json-parse';
 import { DI } from '@/di-symbols.js';
-import type { FollowingsRepository, NotesRepository, EmojisRepository, NoteReactionsRepository, UserProfilesRepository, UserNotePiningsRepository, UsersRepository, FollowRequestsRepository } from '@/models/_.js';
+import type { FollowingsRepository, NotesRepository, EmojisRepository, NoteReactionsRepository, UserProfilesRepository, UserNotePiningsRepository, UsersRepository, FollowRequestsRepository, MiMeta } from '@/models/_.js';
 import * as url from '@/misc/prelude/url.js';
 import type { Config } from '@/config.js';
 import { ApRendererService } from '@/core/activitypub/ApRendererService.js';
@@ -42,6 +42,9 @@ export class ActivityPubServerService {
 		@Inject(DI.config)
 		private config: Config,
 
+		@Inject(DI.meta)
+		private meta: MiMeta,
+
 		@Inject(DI.usersRepository)
 		private usersRepository: UsersRepository,
 
@@ -102,6 +105,11 @@ export class ActivityPubServerService {
 
 	@bindThis
 	private inbox(request: FastifyRequest, reply: FastifyReply) {
+		if (this.meta.federation === 'none') {
+			reply.code(403);
+			return;
+		}
+
 		let signature;
 
 		try {
@@ -173,6 +181,11 @@ export class ActivityPubServerService {
 		request: FastifyRequest<{ Params: { user: string; }; Querystring: { cursor?: string; page?: string; }; }>,
 		reply: FastifyReply,
 	) {
+		if (this.meta.federation === 'none') {
+			reply.code(403);
+			return;
+		}
+
 		const userId = request.params.user;
 
 		const cursor = request.query.cursor;
@@ -265,6 +278,11 @@ export class ActivityPubServerService {
 		request: FastifyRequest<{ Params: { user: string; }; Querystring: { cursor?: string; page?: string; }; }>,
 		reply: FastifyReply,
 	) {
+		if (this.meta.federation === 'none') {
+			reply.code(403);
+			return;
+		}
+
 		const userId = request.params.user;
 
 		const cursor = request.query.cursor;
@@ -354,6 +372,11 @@ export class ActivityPubServerService {
 
 	@bindThis
 	private async featured(request: FastifyRequest<{ Params: { user: string; }; }>, reply: FastifyReply) {
+		if (this.meta.federation === 'none') {
+			reply.code(403);
+			return;
+		}
+
 		const userId = request.params.user;
 
 		const user = await this.usersRepository.findOneBy({
@@ -398,6 +421,11 @@ export class ActivityPubServerService {
 		}>,
 		reply: FastifyReply,
 	) {
+		if (this.meta.federation === 'none') {
+			reply.code(403);
+			return;
+		}
+
 		const userId = request.params.user;
 
 		const sinceId = request.query.since_id;
@@ -482,6 +510,11 @@ export class ActivityPubServerService {
 
 	@bindThis
 	private async userInfo(request: FastifyRequest, reply: FastifyReply, user: MiUser | null) {
+		if (this.meta.federation === 'none') {
+			reply.code(403);
+			return;
+		}
+
 		if (user == null) {
 			reply.code(404);
 			return;
@@ -564,6 +597,11 @@ export class ActivityPubServerService {
 		fastify.get<{ Params: { note: string; } }>('/notes/:note', { constraints: { apOrHtml: 'ap' } }, async (request, reply) => {
 			vary(reply.raw, 'Accept');
 
+			if (this.meta.federation === 'none') {
+				reply.code(403);
+				return;
+			}
+
 			const note = await this.notesRepository.findOneBy({
 				id: request.params.note,
 				visibility: In(['public', 'home']),
@@ -594,6 +632,11 @@ export class ActivityPubServerService {
 		fastify.get<{ Params: { note: string; } }>('/notes/:note/activity', async (request, reply) => {
 			vary(reply.raw, 'Accept');
 
+			if (this.meta.federation === 'none') {
+				reply.code(403);
+				return;
+			}
+
 			const note = await this.notesRepository.findOneBy({
 				id: request.params.note,
 				userHost: IsNull(),
@@ -634,6 +677,11 @@ export class ActivityPubServerService {
 
 		// publickey
 		fastify.get<{ Params: { user: string; } }>('/users/:user/publickey', async (request, reply) => {
+			if (this.meta.federation === 'none') {
+				reply.code(403);
+				return;
+			}
+
 			const userId = request.params.user;
 
 			const user = await this.usersRepository.findOneBy({
@@ -661,6 +709,11 @@ export class ActivityPubServerService {
 		fastify.get<{ Params: { user: string; } }>('/users/:user', { constraints: { apOrHtml: 'ap' } }, async (request, reply) => {
 			vary(reply.raw, 'Accept');
 
+			if (this.meta.federation === 'none') {
+				reply.code(403);
+				return;
+			}
+
 			const userId = request.params.user;
 
 			const user = await this.usersRepository.findOneBy({
@@ -674,6 +727,11 @@ export class ActivityPubServerService {
 		fastify.get<{ Params: { acct: string; } }>('/@:acct', { constraints: { apOrHtml: 'ap' } }, async (request, reply) => {
 			vary(reply.raw, 'Accept');
 
+			if (this.meta.federation === 'none') {
+				reply.code(403);
+				return;
+			}
+
 			const acct = Acct.parse(request.params.acct);
 
 			const user = await this.usersRepository.findOneBy({
@@ -688,6 +746,11 @@ export class ActivityPubServerService {
 
 		// emoji
 		fastify.get<{ Params: { emoji: string; } }>('/emojis/:emoji', async (request, reply) => {
+			if (this.meta.federation === 'none') {
+				reply.code(403);
+				return;
+			}
+
 			const emoji = await this.emojisRepository.findOneBy({
 				host: IsNull(),
 				name: request.params.emoji,
@@ -705,6 +768,11 @@ export class ActivityPubServerService {
 
 		// like
 		fastify.get<{ Params: { like: string; } }>('/likes/:like', async (request, reply) => {
+			if (this.meta.federation === 'none') {
+				reply.code(403);
+				return;
+			}
+
 			const reaction = await this.noteReactionsRepository.findOneBy({ id: request.params.like });
 
 			if (reaction == null) {
@@ -726,6 +794,11 @@ export class ActivityPubServerService {
 
 		// follow
 		fastify.get<{ Params: { follower: string; followee: string; } }>('/follows/:follower/:followee', async (request, reply) => {
+			if (this.meta.federation === 'none') {
+				reply.code(403);
+				return;
+			}
+
 			// This may be used before the follow is completed, so we do not
 			// check if the following exists.
 
@@ -752,6 +825,11 @@ export class ActivityPubServerService {
 
 		// follow
 		fastify.get<{ Params: { followRequestId: string; } }>('/follows/:followRequestId', async (request, reply) => {
+			if (this.meta.federation === 'none') {
+				reply.code(403);
+				return;
+			}
+
 			// This may be used before the follow is completed, so we do not
 			// check if the following exists and only check if the follow request exists.